1. Field of the Invention
The present invention generally relates to a liquid crystal display device, and more particularly to a backlight module of a liquid crystal display device including a spacer which is mounted onto the bottom plate of the backlight module from the outward side of the bottom plate.
2. Description of the Related Art
Due to the advance of electronic technology, especially for the popularity of portable electronic products, the requirements of light, compact and low-energy consuming display are gradually increasing. With the advantages of low-energy consuming, low-heat dissipation, light weight and non-luminescence, liquid crystal displays (LCD) have been widely used in the electronic products and even have replaced the traditional CRT displays.
In general, a liquid crystal display usually includes a backlight module for providing light to its liquid crystal panel. However, the liquid crystal display may use different kinds of backlight modules depending on its use and size. There are two main types for these backlight modules, i.e. a direct back light type (or direct type) and an edge light type (or side light type).
Referring to FIG. 1, it depicts a direct back light type backlight module of conventional liquid crystal display device 100. The liquid crystal display device 100 includes a backlight module 102, an optical film set 104, a liquid crystal panel 106 and a frame 108. The back light module 102 is disposed under the liquid crystal panel 106 for distributing the light from a light source uniformly over the surface of the liquid crystal panel 106. The back light module 102 includes a metal housing 103 and a plurality of lamps 110 disposed on an inward side of the metal housing 103. The optical film set 104 is disposed between the backlight module 102 and the liquid crystal panel 106 and includes a diffusing plate 104a located on the back light module 102, a diffusing sheet 104b located on the diffusing plate 104a and a prism sheet 104c located on the diffusing sheet 104b. The frame 108 is disposed on the liquid crystal panel 106 and the optical film set 104 and joined with the backlight module 102 for fixing the liquid crystal panel 106 and the optical film set 104 to the backlight module 102.
Referring to FIG. 2, the lamps 110 are separately disposed in a cavity 105 formed by the metal housing 103 and located under a display region of the liquid crystal panel 106 for uniformly distributing the generated light to the liquid crystal panel 106.
The liquid crystal display has a tendency to develop the large dimension, and therefore the requirement of the illumination is increasingly high as the dimension is increasingly large. Particularly, a direct back light type backlight module is applied to the liquid crystal display with large dimension, and therefore the direct back light type backlight module is increasingly important. However, the light emitting area of the direct back light type backlight module is increasingly large, but the thickness of the direct back light type backlight module is not changed. Thus, the structural strength of the direct back light type backlight module is not high enough such that it is easily deformed. In order to solve the problem of deformation, the direct back light type backlight module is provided with a plurality of spacers disposed therein for increasing the structural strength of the direct back light type backlight module.
Furthermore, referring to FIG. 2 again, there must be a predetermined distance between each lamp 110 and the diffusing plate 104a, and therefore the bottom plate 103a of the metal housing 103 is provided with at least one spacer 112 for supporting the diffusing plate 104a such that there can be the predetermined distance between each lamp 110 and the diffusing plate 104a. The metal housing 103 is coated with an adhesive layer (not shown), and the spacer 112 is mounted on the bottom plate 103a of the metal housing 103 by means of the adhesive layer.
Recently, when the optical film set is assembled to the direct back light type backlight module, the spacer 112 is firstly put in the metal housing 103 by a front putting manner (i.e. the front putting manner is that the spacer 112 is put in the metal housing 103 from the upward side of the bottom plate 103a) and is then mounted on the bottom plate 103a of the metal housing 103, and the diffusing plate 104a, the diffusing sheet 104b and the prism sheet 104c are finally disposed on the backlight module 102. However, the diffusing plate 104a and the optical films must be positioned by a fine-tuning action, and the fine-tuning action may cause the spacer 112 to scrape the surface of the diffusing plate 104a, thereby resulting in a scrape on the diffusing plate 104a and further resulting in bad display quality.
Accordingly, there exists a need for a backlight module including a spacer which is mounted onto the bottom plate of the backlight module from the outward side of the bottom plate.